Kelly Holmes revealed yesterday how her preparations for next month's Olympic Games have become shrouded with worry about her form in the 1500 metres, the event she hopes to concentrate on in Athens.

Holmes, who won 800m bronze in Sydney four years ago, has become so concerned that she has been unable to sleep and traces her problems back to March when she fell during the final of the 1500m at the world indoor championships in Budapest.

"At the moment I do not feel I have shown I can be a medallist in Athens [in the 1500m], except what you can base on my past history," she said yesterday. "Only I can deal with it but it is hard because I have put pressure on myself to perform."

Athens will be the last Olympics for Holmes, who is 34, and she has always longed to win the Olympic or the world title at 1500m, where she is a double Commonwealth champion.

But she is ranked only 11th in the world this year - and second in Britain behind Hayley Tullett - and to make matters worse she has suffered a recurrence of a calf injury.

She is set to race over 800m in tomorrow's Norwich Union International in Birmingham but will test out the injury this morning before confirming her participation.

Then she has two races left before the Olympics, both at 1500m, at next Friday's Norwich Union London Grand Prix at Crystal Palace and then the following week in Zurich.

Holmes, who is also running in the 800m in Athens, picked herself up in Budapest but finished ninth. She said: "I thought I was capable of winning a gold medal then. I had no problems leading up to that and then, during the race, it is wham, bam and I am on the floor.

"I have now been going into the races thinking I won't get into trouble, I won't do this or that and I am getting knackered. I am thinking if I am going to do anything at the Olympics, I am going to have run under four minutes and I am putting even more pressure on myself.

"In the 1500m I have felt that I have been too aware of everyone else and everything that is going on in the race. That is not usually my style.

"I have never had this problem before. It is my last Olympics and I feel that I have to get it right. I don't know why it is happening and for some reason the pressure of the Olympics is getting to me.

"In Madrid last weekend I was focused before I started on what I would do. Then, as soon as the gun went, I ended up right at the back of the field and had to pass about eight people with 200m to go and the leader had got ahead.

"The time was nothing fantastic. I had run faster in training only three days before, so there is some barrier there for some reason. It is a psychological thing because my training has gone really well."

Turkey's Elvan Abeylegesse leads the world rankings this season with 3.58.28 and Holmes' best is 4.03.73.

Holmes is one of the great fighters of the British team. She has been through so much emotional turmoil it is remarkable she is still running. Notably on the last occasion that Athens staged a major athletics event, the 1997 world championships, she sustained an injury in the heats of the 1500m when favourite for gold.

If she runs tomorrow, she will face the European champion Jolanda Ceplak at a meeting that will see the British debut of Malachi Davis.

He will compete in the 4x400m relay, five days after gaining his Olympic selection, in a match against the United States, and European and Commonwealth Select teams.

The men's 100m sees Kim Collins, the world and Commonwealth champion - who has hardly made an impression on the sprinting scene this year - against Darren Campbell, Jason Gardener and Mark Lewis-Francis. Collins believes all three of the Britons can make the Olympic final.

The women's 400m will provide a good test for Christine Ohuruogu, the unexpected winner of the Olympic trials, when she meets, among others, the top Jamaican Nadia Davy. The three biggest names in women's pole vaulting also meet for the first time this season: Russia's world record holder Svetlana Feofanova, the former world record holder Yelena Isinbayeva and Stacy Dragila, the Olympic champion, of the United States.